Express this product in scientific notation: $(6.90\times 10^{2})\times (9.00\times 10^{4})$
Solution: Start by collecting like terms together. $= (6.90\times 9.00) \times (10^{2}\times 10^{4})$ When multiplying exponents with the same base, add the powers together. $= 62.1 \times 10^{2\,+\,4}$ $= 62.1 \times 10^{6}$ To write the answer correctly in scientific notation, the first number needs to be between $1$ and $10$ . In this case, we need to move the decimal one position to the left without changing the value of our answer. $ $ We can use the fact that $62.1$ is the same as $6.210 \times 10$ $ = {6.210 \times 10} \times 10^{6} $ $= 6.210\times 10^{7}$